Showing papers on "Osmium published in 1996"
Patent•
01 Aug 1996TL;DR: Ruthenium and osmium carbene compounds that are stable in the presence of a variety of functional groups and can be used to catalyze olefin metathesis reactions on unstrained cyclic and acyclic olefins are disclosed.
Abstract: Ruthenium and osmium carbene compounds that are stable in the presence of a variety of functional groups and can be used to catalyze olefin metathesis reactions on unstrained cyclic and acyclic olefins are disclosed. Also disclosed are methods of making the carbene compounds. The carbene compounds are of the formula
where M is Os or Ru; R 1 is hydrogen; R is selected from the group consisting of hydrogen, substituted or unsubstituted alkyl, and substituted or unsubstituted aryl; X and X 1 are independently selected from any anionic ligand; and L and L 1 are independently selected from any neutral electron donor. The ruthenium and osmium carbene compounds of the present invention may be synthesized using diazo compounds, by neutral electron donor ligand exchange, by cross metathesis, using acetylene, using cumulated olefins, and in a one-pot method using diazo compounds and neutral electron donors. The ruthenium and osmium carbene compounds of the present invention may be used to catalyze olefin metathesis reactions including, but not limited to, ROMP, RCM, depolymerization of unsaturated polymers, synthesis of telechelic polymers, and olefin synthesis.
260 citations
TL;DR: Peridotite xenoliths from the Cascade arc in the United States and in the Japan arc have neodymium and osmium isotopic compositions that are consistent with addition of 5 to 15 percent of subducted material to the present-day depleted mantle, suggesting that Osmium can be partitioned into oxidized and chlorine-rich slab-derived fluids or melts.
Abstract: Peridotite xenoliths from the Cascade arc in the United States and in the Japan arc have neodymium and osmium isotopic compositions that are consistent with addition of 5 to 15 percent of subducted material to the present-day depleted mantle. These observations suggest that osmium can be partitioned into oxidized and chlorine-rich slab-derived fluids or melts. These results place new constraints on the behavior of osmium (and possibly other platinum group elements) during subduction of oceanic crust by showing that osmium can be transported into the mantle wedge.
250 citations
TL;DR: The allenylidene complexes [M(CCCR2)(η5-C9H7)L2][PF6] (M = Ru, L = PPh3, L2 = 1,2-bis(diphenylphosphino)ethane (dppe), bis(diphosphino)-methane(dppm), R2 = 2 Ph (1a−c), C12H8 (2,2'-biphenyldi)
159 citations
115 citations
TL;DR: In this article, the reaction of the alkenyl complex OsCl(E-CHCHPh)(CO)(PiPr3)2 (1) with phenyllithium gives OsH{C6H4-2-(E-ChCHPh)](CO)(piPr3)-2 (2).
Abstract: Reaction of the alkenyl complex OsCl(E-CHCHPh)(CO)(PiPr3)2 (1) with phenyllithium gives OsH{C6H4-2-(E-CHCHPh)}(CO)(PiPr3)2 (2). The structure of 2 (isomer 2a) has been determined by X-ray diffraction: triclinic, P1, a = 9.230(1) A, b = 10.092(1) A, c = 18.525(2) A, α = 88.667(7)°, β = 87.172(7)°, γ = 71.110(6)°, V = 1630.6(3), Z = 2, R (F, Fo ≥ 4σ(Fo)) = 4.01, wR (F2, all reflections) = 9.94%. The geometry around the osmium can be described as a distorted octahedron with the two triisopropylphosphine ligands occupying two relative trans positions. The remaining perpendicular plane is formed by the carbonyl and the 2-(E-1‘-styryl)phenyl ligands mutually trans disposed, the hydride ligand and one olefinic hydrogen of the 2-(E-1‘-styryl)phenyl ligand, which shows an agostic interaction with the osmium atom (distance 2.05(7) A). The solutions of 2 show equilibria between the agostic isomer (2a) and a nonagostic isomer (2b). The thermodynamic magnitudes involved in the equilibrium as well as the activation p...
63 citations
TL;DR: In this paper, the 19F NMR spectra of the fluorine-bridged diosmium cation F(cis-OsO2F3)2+SbF11-salt were obtained.
Abstract: Osmium dioxide tetrafluoride, cis-OsO2F4, reacts with the strong fluoride ion acceptors AsF5 and SbF5 in anhydrous HF and SbF5 solutions to form orange salts. Raman spectra are consistent with the formation of the fluorine-bridged diosmium cation F(cis-OsO2F3)2+, as the AsF6- and Sb2F11- salts, respectively. The 19F NMR spectra of the salts in HF solution are exchange-averaged singlets occurring at higher frequency than those of the fluorine environments of cis-OsO2F4. The F(cis-OsO2F3)2+Sb2F11- salt crystallizes in the orthorhombic space group Imma. At −107 °C, a = 12.838(3) A, b = 10.667(2) A, c = 11.323(2) A, V = 1550.7(8) A3, and Z = 4. Refinement converged with R = 0.0469 [Rw = 0.0500]. The crystal structure consists of discrete fluorine-bridged F(cis-OsO2F3)2+ and Sb2F11- ions in which the fluorine bridge of the F(cis-OsO2F3)2+ cation is trans to an oxygen atom (Os−O 1.676 A) of each OsO2F3 group. The angle at the bridge is 155.2(8)° with a bridging Os---Fb distance of 2.086(3) A. Two terminal fluor...
50 citations
TL;DR: In this article, a quasi-reversible one-electron cyclic voltammetric couple (E 1/2 = 0.50-0.70 V) was obtained for the Schiff bases of 2,6-diformyl-4-methylphenol with M(PPh 3 ) 3 X 2 in ethanol.
43 citations
TL;DR: In this article, the preparations of several new (pentamethylcyclopentadienyl)osmium(II) complexes from the osmium(III) compound (C5Me5)2Os2Br4 are described.
31 citations
TL;DR: Simple and rapid determination of ruthenium and osmium in a calibration standard solution of the noble metals for plasma spectroscopy using the proposed methods has been achieved.
26 citations
TL;DR: In this article, ab initio calculations with effective core potentials were performed on pentahydrido(cyclopentadienyl)osmium(VI), CpOsH5, to determine its structure, vibrational spectrum, and rearrangement mechanism.
Abstract: The recent synthesis of (pentamethylcyclopentadienyl)osmium(VI) pentahydride (Cp*OsH5) completes the series of high-oxidation-state cyclopentadienyl metal polyhydrides. A single hydride resonance in the proton NMR spectrum indicated that the complex contained either five equivalent hydride ligands or inequivalent hydrides in rapid exchange. Vibrational studies were inconclusive as to whether the molecule adopted a C5v (pseudo-pentagonal-pyramid with the Cp ring occupying the axial position) or a pseudo-C4v (pseudo-octahedral with the Cp ring considered as occupying one site) orientation in the ground state. In this study, ab initio calculations with effective core potentials were performed on pentahydrido(cyclopentadienyl)osmium(VI), CpOsH5, to determine its structure, vibrational spectrum, and rearrangement mechanism. Geometry optimizations at the Hartree−Fock (HF) and second-order Moller−Plesset (MP2) levels of theory and energy calculations at the MP3, configuration interaction singles and doubles (CIS...
25 citations
TL;DR: In this article, the first-order dependence of the reaction rate on |indole| 0 and |oxidant| 0, a fractional order on |Os(VIII)|, and an inverse firstorder on |OH−| has been shown.
Abstract: The kinetics of oxidation of the title substrates by sodium N-haloarylsulfonamides (or ary-N-haloamines), chloramine-T (CAT), bromamine-T (BAT), chloramine-B (CAB), and bromamine-B (BAB), catalyzed by osmium(VIII) in alkaline medium has been studied at 30°C. The corresponding oxindoles and arylsulfonamides have been characterized as reaction products. The reaction rate shows a first-order dependence each on |indole|0 and |oxidant|0, a fractional-order on |Os(VIII)|, and an inverse first-order on |OH−|. Addition of arylsulfon-amide, chloride and bromide, and variation of ionic strength of the medium have no effect on the reaction rate. There is a negative effect of dielectric constant of the solvent. Activation parameters have been calculated from the Arrhenius and Eyring plots. Hammett correlation of substituent effects indicates an LFE relationship with ρ = −1.0, showing the formation of an electron deficient transition state. From enthalpy-entropy relationships and Exner correlations, the isokinetic temperatures (333 K and 326 K) have been determined for the reactions of CAT and BAT, respectively. Proton inventory studies in H2O-D2O mixtures have shown the involvement of a single exchangeable proton of OH− ion in the transition state. A mechanism consistent with the observed kinetics has been proposed. © 1996 John Wiley & Sons, Inc.
Journal Article•
TL;DR: In this article, the adsorption and desorption processes of a new series of redox-active transition metal complexes of the type [Os(bpy)2Cl(Py(CH2)nSH)](PF6), with n = 4, 6, or 9, capable of forming adsorbed monolayers on gold and platinum electrodes have been studied using cyclic voltammetry.
TL;DR: In this paper, a 12-vertex closo-hydridometallacarboranes 3,1,2-[(PPh3)2OsHXC2B9H11] (1a,b: X = Cl, H) and 3, 1,2]-(Pph3) 2OsH2-1, 2-Me2C2C9H9](1c) have been synthesized via oxidative addition of K+ salts of the nido-carborane anions [nido-7,
TL;DR: Cryofixation followed by freeze substitution in osmium tetroxide was evaluated as a method for preparing biological specimens for immunoelectronmicroscopy and the results suggest that the partial removal of the plastic by etching of freeze‐substituted tissue can be explored for exposing fine biological structures for observation with atomic force microscopy.
Abstract: Cryofixation followed by freeze substitution in osmium tetroxide was evaluated as a method for preparing biological specimens for immunoelectronmicroscopy. Samples were rapidly frozen by impact onto a sapphire block cooled with liquid nitrogen, substituted at −80°C in acetone containing osmium tetroxide, and embedded in epoxy resin. With this protocol, excellent ultrastructure can be combined with localization of antigens that otherwise would be inactivated by the osmium, but labeling may need to be enhanced by chemically etching the sections prior to staining. The effects of etching on various structures in the sections were investigated by examining the sections with atomic force microscopy, an approach that yields three-dimensional views of the surface of the section. A considerable part of the section was removed or collapsed by the etching, and these effects occurred differentially in several components of the tissue and with different etching protocols. Nevertheless, the results suggest that the partial removal of the plastic by etching of freeze-substituted tissue can be explored as a method for exposing fine biological structures for observation with atomic force microscopy. © 1996 Wiley-Liss, Inc.
Patent•
11 Jan 1996
TL;DR: In this paper, the preparation of epoxide from olefins, hydrogen and oxygen is carried out using an oxidation catalyst based on titanium or vanadium silicalite with zeolite structure.
Abstract: The preparation of epoxide from olefins, hydrogen and oxygen is carried out using an oxidation catalyst based on titanium or vanadium silicalite with zeolite structure, which contains 0.1-20 wt.% of platinum metals(s) selected from ruthenium, rhodium, palladium, osmium, iridium and platinum, each of which is present in more than one different bond energy state. An inert carrier gas selected from nitrogen, noble gases, carbon dioxide and 1-8 carbon C hydrocarbons may be used. The molar ratio of H2:O2 is 1:(1-10) and of inert gas to olefin > 20:1. The molar ratio of O2 to olefin or olefin and inert gas, if used, is < 1:3-10. The zeolite is mentioned.
TL;DR: In this paper, the isotopic composition and concentration of seawater osmium were reported for the first time, and the isolation step involved anion exchange and the distillation of Osmium tetroxide.
Abstract: Methods to ascertain the concentration and isotopic composition of seawater osmium are described. The isolation step involves anion exchange and the distillation of osmium tetroxide. The determinative step utilizes resonance ionization mass spectrometry. The isotopic composition and concentration of osmium are reported for the first time.
TL;DR: A terdentate polypyridine ligand, 2,6-bis(7′-methyl-4′-phenyl-2′-quinolyl) pyridine (bmpqpy), was synthesized in this article.
TL;DR: In this article, the reactivity of some ruthenium and osmium carbonyl clusters towards unsaturated organic ligands is described, and the reaction is shown to be reversible.
Patent•
16 Jul 1996TL;DR: In this article, the authors proposed a catalyst for the dehydrogenation of C3-C20 paraffins, which is based on a support comprising at least one metal from group VIII of the periodic classification of elements such as platinum, palladium, ruthenium, rhodium, nickel, osmium or iridium.
Abstract: The invention concerns a catalyst containing a support comprising at least one metal from group VIII of the periodic classification of elements such as platinum, palladium, ruthenium, rhodium, nickel, osmium or iridium, at least one additional metal selected from the group formed by groups IIB, IIIA, IVA, IVB, VA, VB, VIIB and VIII and at least one metal selected from the group formed by alkali and alkaline-earth metals, characterized in that said alkali or alkaline-earth metal is at least partially contained in the support in the form of an aluminate. The invention also concerns the preparation and use of said catalyst for dehydrogenation of C3-C20 paraffins.
TL;DR: Olefins react with ethyl diazoacetate in the presence of a catalytic amount of [OsCl2(p-cymene)]2 to produce the corresponding cyclopropanes in good yields.
Book•
01 Jan 1996
TL;DR: Chromium-, Molybdenum- and Tungsten-Hydrogen Manganese-, Technetium- and Rhenium-hydrogen Iron (Ruthenium and Osmium)-Hydrogen Systems Cobalt-, Rhodium-and Iridium-Hydroxide-Nic Nickel-Nickel-Naphroxide System Platinum and Palladium-H, Pd-D and PdT Systems.
Abstract: Chromium-, Molybdenum- and Tungsten-Hydrogen Manganese-, Technetium- and Rhenium-Hydrogen Iron (Ruthenium and Osmium)-Hydrogen Systems Cobalt-, Rhodium- and Iridium-Hydrogen Nickel-Hydrogen System Platinum and Palladium-Hydrogen Palladium-Hydrogen System 1st PART of: Platinum and Palladium-Hydrogen: Thermodynamic Parameters of the Pd-H, Pd-D and Pd-T Systems 2nd PART of: Platinum and Palladium-Hydrogen: Lattice Structure and Expansion Effects 3rd PART of: Platinum and Palladium-Hydrogen: Elastic and Anelastic Studies Copper- Silver- and Gold-Hydrogen
TL;DR: In this article, a cyclic voltammetry of osmium phthalocyanine complexes, (CN) 2 Os II PC] 2− and (py) 2 OS II Pc (PC) 2−, was performed and two reduction couples were obtained in acetonitrile and dimethy1formamide.
TL;DR: In this article, a high-yield procedure was described for the preparation from [M(CO)3Cl2]2 (M = Ru, Os) and aqueous NaOH, of the new water-soluble and air-stable species [Ru (CO)2Cl(OH)]n, [Ru( CO)2(OH)2] 2]n,
TL;DR: The relatively strong binding of carbon monoxide to osmium(III) is proposed to be an important factor in avoiding dimerization of the reaction intermediates.
Abstract: trans-Dichloro-, trans-dibromo-, and trans-diiodoosmium(IV) tetraarylporphyrins were obtained by extremely facile synthetic routes directly from the reactions of the corresponding (carbonyl)osmium(II) complexes with CCl(4), CBr(4), and CI(4), respectively. At short reaction times, appreciable amounts of intermediates-one for each reaction-were observed by spectroscopic investigations. These intermediates were shown to be (carbonyl)(halo)(porphyrinato)osmium(III) complexes by independent preparation of an authentic (carbonyl)(bromo)(porphyrinato)osmium(III) complex, which was identical to the reaction intermediate in the reaction of CBr(4) and very similar to those of the other reactions. This provided strong evidence for the reaction mechanism, two stepwise one-electron oxidations of the metal ion. The relatively strong binding of carbon monoxide to osmium(III) is proposed to be an important factor in avoiding dimerization of the reaction intermediates.
TL;DR: In this paper, it was shown that the reaction is accompanied by redistribution of the PPh3 ligand, and as a result, compound 1 exists in solution as three isomers (1a−c) due to the presence and disposition of a phosphine ligand on both Os and Pt.
Patent•
05 Jul 1996
TL;DR: In this article, the use of chromatographic media for interseparation of the PGMs from a reduced feed which are eluted in the order of iridium, rhodium and ruthenium together, followed by palladium, platinum and osmium.
Abstract: This invention relates to a method of interseparation of platinum group metals, and in particular to the use of chromatographic media for interseparation of the PGMs from a reduced feed which are eluted in the order of iridium, rhodium and ruthenium together, followed by palladium, platinum and osmium.
TL;DR: Osmium tetroxyde-catalyzed dihydroxylation of allenic compounds in the presence of N-Methylmorpholine Oxide leads to α-ketols, which is applicable to allenic α-amino acid precursors.
01 Apr 1996-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, M-shell X-ray production cross sections for Os, Au and Th targets were measured for C, N and O ions at incident energies from 1.2 MeV to about 36 MeV.
Abstract: M-shell X-ray production cross sections for Os, Au and Th targets were measured for C, N and O ions at incident energies from 1.2 MeV to about 36 MeV. Experimental M-shell ionization cross sections, derived by using the effective M-shell fluorescence yields, are compared with the prediction of the SCA calculations with relativistic hydrogenic wave functions. The calculations were performed both in the separated-atom (SA) and united-atom (UA) limits to simulate the binding effect. Generally, the data show better agreement with the SCA-UA cross sections for lower energies and with the SCA-SA predictions for higher energies. For C and O impact on the Au target at about 2 MeV/amu the present data are compared with available experimental results and theoretical predictions of the ECPSSR theory.